hush/networking/hostname.c
Michael Tokarev e9355c4326 hostname: do not use gethostbyname() for "hostname -s"
There's no reason to call gethostbyname() on the value returned
by uname() when asked just for a short name of a host.  This may
also be wrong, when uname is set to one value, but in /etc/hosts
(or elsewhere) the "canonical" name is different.  This is often
the case for localhost entry in /etc/hosts:

  127.0.0.1     localhost       myname

With this content of /etc/hosts, and uname being set to myname,
busybox hostname -s will return localhost, while regular
hostname utility returns myname.

Fix this by not calling gethostbyname() for the simple
'hostname -s' use.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2013-12-17 19:13:45 +01:00

180 lines
5.0 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini hostname implementation for busybox
*
* Copyright (C) 1999 by Randolph Chung <tausq@debian.org>
*
* Adjusted by Erik Andersen <andersen@codepoet.org> to remove
* use of long options and GNU getopt. Improved the usage info.
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//usage:#define hostname_trivial_usage
//usage: "[OPTIONS] [HOSTNAME | -F FILE]"
//usage:#define hostname_full_usage "\n\n"
//usage: "Get or set hostname or DNS domain name\n"
//usage: "\n -s Short"
//usage: "\n -i Addresses for the hostname"
//usage: "\n -d DNS domain name"
//usage: "\n -f Fully qualified domain name"
//usage: "\n -F FILE Use FILE's content as hostname"
//usage:
//usage:#define hostname_example_usage
//usage: "$ hostname\n"
//usage: "sage\n"
//usage:
//usage:#define dnsdomainname_trivial_usage NOUSAGE_STR
//usage:#define dnsdomainname_full_usage ""
#include "libbb.h"
static void do_sethostname(char *s, int isfile)
{
// if (!s)
// return;
if (isfile) {
parser_t *parser = config_open2(s, xfopen_for_read);
while (config_read(parser, &s, 1, 1, "# \t", PARSE_NORMAL & ~PARSE_GREEDY)) {
do_sethostname(s, 0);
}
if (ENABLE_FEATURE_CLEAN_UP)
config_close(parser);
} else if (sethostname(s, strlen(s))) {
// if (errno == EPERM)
// bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
bb_perror_msg_and_die("sethostname");
}
}
/* Manpage circa 2009:
*
* hostname [-v] [-a] [--alias] [-d] [--domain] [-f] [--fqdn] [--long]
* [-i] [--ip-address] [-s] [--short] [-y] [--yp] [--nis]
*
* hostname [-v] [-F filename] [--file filename] / [hostname]
*
* domainname [-v] [-F filename] [--file filename] / [name]
* { bbox: not supported }
*
* nodename [-v] [-F filename] [--file filename] / [name]
* { bbox: not supported }
*
* dnsdomainname [-v]
* { bbox: supported: Linux kernel build needs this }
* nisdomainname [-v]
* { bbox: not supported }
* ypdomainname [-v]
* { bbox: not supported }
*
* -a, --alias
* Display the alias name of the host (if used).
* { bbox: not supported }
* -d, --domain
* Display the name of the DNS domain. Don't use the command
* domainname to get the DNS domain name because it will show the
* NIS domain name and not the DNS domain name. Use dnsdomainname
* instead.
* -f, --fqdn, --long
* Display the FQDN (Fully Qualified Domain Name). A FQDN consists
* of a short host name and the DNS domain name. Unless you are
* using bind or NIS for host lookups you can change the FQDN and
* the DNS domain name (which is part of the FQDN) in the
* /etc/hosts file.
* -i, --ip-address
* Display the IP address(es) of the host.
* -s, --short
* Display the short host name. This is the host name cut at the
* first dot.
* -v, --verbose
* Be verbose and tell what's going on.
* { bbox: supported but ignored }
* -y, --yp, --nis
* Display the NIS domain name. If a parameter is given (or --file
* name ) then root can also set a new NIS domain.
* { bbox: not supported }
* -F, --file filename
* Read the host name from the specified file. Comments (lines
* starting with a `#') are ignored.
*/
int hostname_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int hostname_main(int argc UNUSED_PARAM, char **argv)
{
enum {
OPT_d = 0x1,
OPT_f = 0x2,
OPT_i = 0x4,
OPT_s = 0x8,
OPT_F = 0x10,
OPT_dfi = 0x7,
};
unsigned opts;
char *buf;
char *hostname_str;
#if ENABLE_LONG_OPTS
applet_long_options =
"domain\0" No_argument "d"
"fqdn\0" No_argument "f"
//Enable if seen in active use in some distro:
// "long\0" No_argument "f"
// "ip-address\0" No_argument "i"
// "short\0" No_argument "s"
// "verbose\0" No_argument "v"
"file\0" No_argument "F"
;
#endif
/* dnsdomainname from net-tools 1.60, hostname 1.100 (2001-04-14),
* supports hostname's options too (not just -v as manpage says) */
opts = getopt32(argv, "dfisF:v", &hostname_str);
argv += optind;
buf = safe_gethostname();
if (applet_name[0] == 'd') /* dnsdomainname? */
opts = OPT_d;
if (opts & OPT_dfi) {
/* Cases when we need full hostname (or its part) */
struct hostent *hp;
char *p;
hp = xgethostbyname(buf);
p = strchrnul(hp->h_name, '.');
if (opts & OPT_f) {
puts(hp->h_name);
} else if (opts & OPT_s) {
*p = '\0';
puts(hp->h_name);
} else if (opts & OPT_d) {
if (*p)
puts(p + 1);
} else /*if (opts & OPT_i)*/ {
if (hp->h_length == sizeof(struct in_addr)) {
struct in_addr **h_addr_list = (struct in_addr **)hp->h_addr_list;
while (*h_addr_list) {
printf(h_addr_list[1] ? "%s " : "%s", inet_ntoa(**h_addr_list));
h_addr_list++;
}
bb_putchar('\n');
}
}
} else if (opts & OPT_s) {
strchrnul(buf, '.')[0] = '\0';
puts(buf);
} else if (opts & OPT_F) {
/* Set the hostname */
do_sethostname(hostname_str, 1);
} else if (argv[0]) {
/* Set the hostname */
do_sethostname(argv[0], 0);
} else {
/* Just print the current hostname */
puts(buf);
}
if (ENABLE_FEATURE_CLEAN_UP)
free(buf);
return EXIT_SUCCESS;
}